In the folk belief there are two relations to bear. The first is where one treat the bear as an animal. According to the folk belief there was a special fear associated with bear and its relation to pregnant women. A bear could kidnap and bury or tear apart a pregnant woman, why are not told.
A bear could also kidnap boy child and raise him:
There was a bear who took a wife who was with child and tore her to pieces. The bear took the child with her to the den and there the boy grew up until he was three years old. Then some people found the den and took the child from the bear.
The boy was big and beautiful and he did not seem to starve. They killed the bear, even though the boy was trying to protect it.
The boy grew big and strong and was not afraid of anyone and when he met a bear he always spent some time with the animal.
Source: Ivar Aasen: Norske minnestykke I
The second factor is how humans can shapeshifte into a bear, this person wore a bearskin to take revenge or scare someone. The only thing that could trap a shapeshifter, was bullets made of silver. While the werewolf was a curse thrown upon a person, transforming into a bear was an act of will, and an ability of some humans.
There was once a man who never could keep the bear away his horses. The man did not know what to doFinally he heard talk of a horse that bears could not overcome. This horse he bought and immediately traveled with it to a pasture where he knew the bear would come. The man stayed there to see what would happen.
After a while the bear arrived and there was a fight between the bear and the horse. The horse defended itself well and the bear was finally tired and went away from the horse to a hill and sat down.
The man had been hiding himself and followed closely with his eyes the bear. But then he saw to his amazement see that the bear turned into a man, but not the whole man. The legs still belonged to a bear. The ”bearman” took out a pipe and began to smoke it. The man realized that there was witchcraft here. He raised his gun and shot the bear so it fell forward. When he arrived at the place where the bear was lying dead, he saw that it was his own neighbor lying where he expected to find the bear.
Source: Naturrigerne i den norske folketro Joh. Th. Storaker